fix typo and refactor

Signed-off-by: ekexium <eke@fastmail.com>

txnkv/transaction/2pc.go

@@ -1343,13 +1343,16 @@ func keepAlive(
 					}
 					return
 				}
-			} else {
-				keepFail = 0
-				metrics.TxnHeartBeatHistogramOK.Observe(time.Since(startTime).Seconds())
+				continue
 			}
 
-			// broadcast to all stores
-			if err != nil && isPipelinedTxn {
+			keepFail = 0
+			metrics.TxnHeartBeatHistogramOK.Observe(time.Since(startTime).Seconds())
+			// Broadcast to all stores only when the heartbeat succeeds.
+			// This ensures that PK is the single source of truth for transaction status on the
+			// TiKV side. It prevents potential inconsistencies where the cached information might
+			// be more up-to-date than the info stored in the PK.
+			if isPipelinedTxn {
 				broadcastToAllStores(
 					c.txn,
 					c.store,